The present application pertains generally to displaying and reviewing recorded video and, in particular, to displaying and reviewing recorded video via video timelines containing thumbnails. As used herein thumbnail means a video still, also known as a snapshot, sampled from a video recording, which represents a time bound segment of the video recording. Depending on the zoom setting on the timeline, each thumbnail may represent a different timespan, for example ranging from one minute to one hour to one day, of recorded video.
Using thumbnails to represent recorded video provides users with a direct, intuitive method for reviewing events. However, a thumbnail timeline presents several competing requirements. A user needs the thumbnails to be large enough so that he can perceive differences in the scene over time. The timeline also needs to be scaled with sufficient granularity so that a user can navigate with precision to a particular point in time. For example, a user may use a scrubber which is a vertical control that can be repositioned horizontally on the timeline. If a user moves the scrubber to the left, the video timeline is moved back in time thereby rewinding the video. If a user moves the scrubber to the right, the video timeline is moved forward in time thereby causing the video to fast-forward. The timeline needs to be proportional, with each thumbnail representing a known timespan so that the scrubbing navigation will feel natural and predictable.
A frequent requirement when reviewing security video is to locate footage of an event where the exact time of the incident is not known. A user comes to the system with a broad time frame and a more or less precise idea of what to look for. In this situation, displaying thumbnails that represent different points in a recorded sequence of events provides users with a direct, intuitive method for reviewing a video recording. The thumbnails provide guideposts, to help the user know where to position the scrubber. If the user sees something of interest, he can drag the scrubber to that point. As the user moves the scrubber along the timeline, the video in the workspace updates.
On the other hand, there may be gaps in the timeline because the video was set to record only on alarm or motion, or because the video has been pruned. In this case, the thumbnail size and timeline granularity would work against the interests of the user, requiring him to scrub at length or click several times to bypass the sections of timeline where no video is available. The user could zoom out to skip over the gaps, but then he must spend time zooming back in to view the fine-grained changes in the scene. Another option would be to program the interface to permanently hide the gaps in the video; however, this would result in losing the predictable linearity of the timeline and the power of the synchronized scrubbing.
Accordingly, there has been a need in the industry for a method and system for efficiently and effectively displaying and reviewing recorded video via timelines containing thumbnails when the video contains intermittent timespans without recorded video.